JP2003316086A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image forming apparatus equipped with an automatic double-sided printing device, where an image on a back side is prevented from being missed or the inside of the apparatus is prevented from being soiled because toner which is not transferred to recording material is scattered inside the apparatus when zero edge printing is selected as a margin at the end of the recording material smaller than the regular one and automatic double-sided printing is performed. <P>SOLUTION: Even when the margin at the end of the recording material narrower than that of the regular recording material is selected in the case of automatic double-sided image formation using an automatic image double- sided device 80, the margin at the end of the image on the back side is set to be wider than that on the side of the recording material on which the image is formed first, or it is set to the regular margin at the end of the image. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an LBP or a copying machine having an electrophotographic image forming means.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a laser beam printer, a developing device for developing a latent image drawn by laser light or the like, and a transfer means for transferring the developed toner image to a recording material, The one having a fixing device for fixing the transferred toner image on the recording material is mainly used.

FIG. 2 shows a conventional laser beam printer as a typical example. The components of the laser beam printer of FIG. 2 will be described below.

In the printer body (image forming apparatus body), a laser scanner 40, a photosensitive drum 41, a printing process unit 45 including a primary charging roller 42 and a developing roller 43, a transfer roller 46, a fixing device 60, and a conveying roller pair. Four
8. A paper feed cassette 50, a paper feed roller (including a pickup roller) 51, etc. are installed.

The sheet-shaped recording materials P stacked and stored in the paper feeding cassette 50 are fed by the paper feeding roller 5 which rotates counterclockwise.
The sheet is fed by 1, is guided to the sheet metal 52, and is fed to the nip portion of the pair of conveying rollers 48.

Next, the recording material P is sent between the photosensitive drum 41 and the transfer roller 46 by the pair of conveying rollers 48.

The photosensitive drum 41 is rotated clockwise, and the surface of the photosensitive drum is uniformly charged to a negative potential by the primary charging roller 42. And on its outer surface,
An electrostatic latent image is sequentially formed by the laser light L from the laser scanner 40, and then the electrostatic latent image is developed by the developing roller 43, so that a toner image is formed by the negatively charged toner. The laser light L is converted into an image-formable signal in the image forming apparatus based on image information formed by a personal computer or the like, and the laser is emitted in accordance with a portion to be printed such as characters or graphics. become.

On the recording material P sent between the photosensitive drum 41 and the transfer roller 46, the toner image on the photosensitive drum 41 is sequentially transferred by the transfer roller 46 to which a positive potential is applied. This transfer roller generally rotates the photosensitive drum quickly.

In general, the transfer roller 46 prevents the photosensitive drum 41 from deteriorating in print quality in order to prevent the print quality from deteriorating, such as a hollow image phenomenon in which a part of toner forming an image is not transferred. Slow, transfer roller 46
Is driven fast. That is, the photosensitive drum 41 acts as a reaction force against the conveyance of the recording material P, and the transfer roller 46 acts as a driving force. By balancing these, the transport speed of the recording material P is configured to be close to the process speed during normal printing.

The transfer roller 46 also serves to convey the recording material.

The recording material P on which the toner image has been transferred in this manner is sent to the fixing device 60, where it is heated and pressed to fix the toner image on the recording material P.

After that, the recording material P is sent to the paper discharge roller 71 by the pair of transport rollers 61, and then discharged onto the paper discharge tray 70 on the upper surface of the printer body by the paper discharge roller 71.

In this conventional laser beam printer, the units such as the printing process unit 45, the fixing device 60, etc., and the roller relations such as the paper feed roller 51, the transfer roller 46, etc. are consumable parts and the life of the product is reduced. It needs several exchanges inside.

Further, in the automatic double-sided device CC for automatically printing on both the front and back sides of the recording material, the recording material which has passed through the fixing device 60 is
The sheet is conveyed to the automatic duplexer 80, inverted, conveyed again to the sheet feeding mechanism, and re-fed. The recording material conveyance route is classified into several types, but is automatically reversed by the automatic double-sided device 80 and is re-fed to perform automatic double-sided printing.

As described above, the image forming apparatus briefly described above protects an image formed on a recording material so that the image formed on the recording material is not damaged from the recording material in order to protect the image in the printing range and protect the image forming apparatus. Image forming is not performed in a range around the material, or a margin of the recording material edge is provided as a prohibited area as shown in FIG. The range of the margin of the end portion of the recording material is each component related to image formation, for example, a sheet feeding device, a writing start position of a laser that forms an electrostatic latent image on a photosensitive drum,
An image is formed at a predetermined position on the recording material due to variations in the positions of the transfer roller as the transfer device, the recording material conveying rollers, etc., and the thrust backlash, etc. This is to prevent scattering. For this reason, it is general to provide margins of about 5 mm width at the end portions of the recording material such as the leading edge, the trailing edge, the left edge, and the right edge in consideration of the mounting tolerance of each component, thrust rattling, and the like. .

However, the image occupies a large amount on the recording material, and the image is cut off by providing a margin on the edge of the recording material, or the name / number for the purpose of classification and sorting is printed using the margin on the edge of the recording material. A zero edge print such as, may be desired depending on the usage of the user.

Therefore, the user can selectively perform the zero edge print in which the image end margin can be made smaller than usual or the image end margin can be arbitrarily set.

[0018]

However, in the above-mentioned conventional example, when the automatic double-sided printing is performed by the image forming apparatus equipped with the automatic double-sided device, a desired recording material end margin is secured on the first printed surface. Therefore, the image is not chipped or the toner that is not transferred to the recording material does not scatter in the image forming apparatus.However, when printing on the back side, the image is chipped or the toner that is not transferred to the recording material enters the image forming apparatus. May be scattered.

This phenomenon occurs even in the margin of the recording material end portion on the back side.
It is remarkable that the trailing edge margin is not secured, and the right edge and left edge margins of the image are likely to occur next.

This is because the unfixed toner on the first printed surface is fixed by the fixing device, and at the same time, the moisture contained in the recording material is vaporized and evaporated by the heat from the fixing roller and the pressure roller. This is because the material shrinks. The rate of shrinkage of the recording material depends on the type, size, weight, water content, etc. of the recording material, so it cannot be said unconditionally, but it is approximately less than 1.0%.

In addition, what is noticeable at the trailing edge of the image is the influence when the toner is transferred to the recording material, which will be described in detail below.

The electrostatic latent image on the photosensitive drum is visualized as a toner image in the developing device and transferred to a recording material. At this time, the toner on the surface of the recording material (the surface on which the image is first formed) in contact with the transfer roller is completely fixed, and the conveyance state between the transfer roller and the recording material is stable. for,
On the surface of the recording material in contact with the photosensitive drum, the unfixed toner is interposed between the recording material and the photosensitive drum, and the unfixed toner serves as a slip agent. Therefore, the higher the proportion of the toner on the recording material, the higher the effect as a slip agent and the smaller the frictional resistance between the recording material and the photosensitive drum. On the contrary, if the proportion of the toner is low, the effect of the slip agent becomes small and the frictional resistance between the recording material and the photosensitive drum becomes large.

That is, while the conveying force from the transfer roller to the recording material is stable and substantially constant, when the frictional resistance of the surface in contact with the photosensitive drum becomes small, the conveying speed of the recording material with respect to the peripheral speed of the photosensitive drum. The difference between the relative speeds of the two becomes large, and the transferred image extends to the recording material. On the contrary, when the frictional resistance of the surface in contact with the photosensitive drum becomes large, the difference in the relative speed of the conveying speed of the recording material with respect to the same speed of the photosensitive drum is small, and the transferred image does not extend to the recording material. .

For this reason, the trailing edge of the recording material has a small trailing edge margin when the printing rate of the image is high, and the trailing edge margin is secured when the printing rate is low.

From the above, when automatic double-sided printing is performed, even if zero edge print is selected as a smaller image end margin, the surface to be printed first does not matter, but is printed next. On the back side, due to the contraction of the recording material and the influence of the expansion due to the image, the image edge portion, especially the image at the rear edge, the right edge, and the left edge is easily chipped, and the toner not transferred to the recording material scatters in the image forming apparatus. When the recording material becomes dirty, the next recording material is soiled, or the scattered toner accumulates, which hinders the conveyance of the recording material and leads to the recording material clogging.

In order to solve the above problems, in the present invention, in an image forming apparatus equipped with an automatic double-sided printing device, a recording material end margin smaller than a normal recording material end margin is selected,
When automatic double-sided printing is performed, the following solution is proposed as a means to prevent the image on the back side from being chipped or toner that is not transferred to the recording material to scatter inside the image forming apparatus and stain the inside of the apparatus. To do.

<Solution 1> An electrostatic latent image is formed on an image carrier made of an optical semiconductor, and the electrostatic latent image is visualized by developing the developer, and then transferred to a recording material as an unfixed developer. , An image forming device that permanently fixes a developer image on a recording material by inserting the recording material between a pair of rotating bodies and applying heat and pressure, and an automatic image that automatically forms an image on both sides of the recording material. It is possible to switch the recording material edge margin, which is equipped with a double-sided device and is provided as the image protection of the image area and the protection area of the image forming apparatus, to a recording material edge margin narrower than the normal recording material edge margin. In the image forming apparatus, even if a recording material edge margin that is narrower than the normal recording material edge margin is selected during automatic double-sided image formation, the image on the back side is printed more than the image edge margin of the recording material surface on which the image is first formed. Widen the edge margins, or use normal image edge margins. By using the image forming apparatus characterized by the above, it is possible to prevent the occurrence of chipping of the image printed on the back side and contamination of the apparatus when toner not transferred to the recording material scatters in the image forming apparatus. To provide.

<Solution 2> An electrostatic latent image is formed on an image carrier made of an optical semiconductor, and the electrostatic latent image is visualized by developing the developer, and then transferred to a recording material as an unfixed developer. , An image forming device that permanently fixes a developer image on a recording material by inserting the recording material between a pair of rotating bodies and applying heat and pressure, and an automatic image that automatically forms an image on both sides of the recording material. It is possible to switch the recording material edge margin, which is equipped with a double-sided device and is provided as the image protection of the image area and the protection area of the image forming apparatus, to a recording material edge margin narrower than the normal recording material edge margin. In the image forming apparatus, when a recording material end margin that is narrower than a normal recording material end margin is selected during automatic double-sided image formation, the recording material end margin is larger than the selected recording material end margin according to the image information on the back side. Image type characterized by setting margins at the edges of recording materials With apparatus, chipping of the image to be printed on the back surface, the toner which is not transferred to the recording material to provide an image forming apparatus capable of preventing apparatus dirt scattered, the occurrence in the image forming apparatus.

<Solution 3> An electrostatic latent image is formed on an image carrier made of an optical semiconductor, and the developer is developed to visualize the electrostatic latent image, and then transferred to a recording material as an unfixed developer. , An image forming device that permanently fixes a developer image on a recording material by inserting the recording material between a pair of rotating bodies and applying heat and pressure, and an automatic image that automatically forms an image on both sides of the recording material. It is possible to switch the recording material edge margin, which is equipped with a double-sided device and is provided as the image protection of the image area and the protection area of the image forming apparatus, to a recording material edge margin narrower than the normal recording material edge margin. In the image forming apparatus, when a recording material edge margin that is narrower than a normal recording material edge margin is selected during automatic double-sided image formation, it is possible to arbitrarily thin back-side image information according to the back-side image information. Printing on the back side by using a characteristic image forming device Missing images, toner not transferred onto the recording material to provide an image forming apparatus capable of preventing the device dirt, the occurrence of scattered in the image forming apparatus be.

[0030]

According to a first aspect of the present invention, after an electrostatic latent image is formed on an image carrier made of an optical semiconductor and a developer is developed to visualize the electrostatic latent image. The recording material is transferred to the recording material as an unfixed developer, the recording material is inserted between a pair of rotating bodies, and heated and pressed to permanently fix the developer image on the recording material. Equipped with an automatic image double-sided device that automatically forms images on both sides of the recording material, the margin of the recording material provided as the image protection of the image area and the protection area of the image forming apparatus is narrower than the ordinary margin of the recording material. In an image forming apparatus capable of switching to a recording material edge margin, even if a recording material edge margin narrower than a normal recording material edge margin is selected during automatic double-sided image formation, the recording material on which the image is first formed Make the back image edge margin wider than the front image edge margin. Ku is characterized by a normal image edge margin.

In a second aspect of the present invention, in the above-mentioned image forming apparatus, even when a recording material end margin narrower than a normal recording material end margin is selected at the time of automatic double-sided image formation, the recording material on the back surface is selected. The edge margin is characterized in that it is wider than the image edge margin of the recording material surface on which the image is first formed, or is a normal image edge margin, excluding the margin at the front of the image.

In a third aspect of the present invention, in the above-mentioned image forming apparatus, even when a recording material edge margin narrower than a normal recording material edge margin is selected during automatic double-sided image formation, the recording material on the back surface is selected. The trailing edge margin is wider than the image edge margin of the recording material surface on which an image is initially formed, or is a normal image edge margin.

In a fourth aspect of the present invention, an electrostatic latent image is formed on an image carrier made of an optical semiconductor and the electrostatic latent image is visualized by developing a developer, and then the toner is not fixed on a recording material. By transferring as a developer, inserting a recording material between a pair of rotating bodies, and applying heat and pressure, an image forming device that permanently fixes the developer image on the recording material is automatically imaged on both sides of the recording material. It is equipped with an automatic image duplexer that performs image formation, image protection of the image area
In an image forming apparatus capable of switching a recording material end margin provided as a protection area of the image forming apparatus to a recording material end margin narrower than a normal recording material end margin, a normal recording medium is formed during automatic double-sided image formation. If a recording material edge margin that is narrower than the recording material edge margin is selected, depending on the image information on the back side,
It is characterized in that a recording material edge margin larger than the selected recording material edge margin is set.

A fifth aspect of the present invention is to form an electrostatic latent image on an image carrier made of an optical semiconductor, visualize the electrostatic latent image by developing a developer, and then fix the latent image on a recording material. By transferring as a developer, inserting a recording material between a pair of rotating bodies, and applying heat and pressure, an image forming device that permanently fixes the developer image on the recording material is automatically imaged on both sides of the recording material. Equipped with an automatic image duplexer that performs image formation, the recording material edge margin that is provided as the image protection of the image area and the protection area of the image forming apparatus is set to a recording material edge margin that is narrower than the normal recording material edge margin. In an image forming apparatus that can be switched, when a recording material end margin that is narrower than a normal recording material end margin is selected during automatic two-sided image formation, the back side image information is displayed according to the back side image information. It is characterized by thinning out arbitrarily.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION An image forming apparatus according to the present invention will be described below in more detail with reference to the drawings. The embodiment described below is embodied in the image forming apparatus shown in FIG. Therefore, a detailed description of the entire image forming apparatus and its functions will be omitted, and the characteristic part of the present invention will be described. Further, members having the same functions as those of the members described above are designated by the same reference numerals, and the description thereof will be omitted.

[First Embodiment] FIG. 1 is a simple flowchart relating to the operation of the image forming apparatus according to the first embodiment of the present invention, which will be described below.

In the structure of the fixing device in this embodiment, the description of the same parts as those in the conventional example will be omitted. Further, description of a widely known electrophotographic image forming apparatus will be omitted.

The image forming apparatus used in this embodiment is A4.
Examination was carried out using LBP-930, which is a laser beam printer manufactured by Canon Sales Co., Ltd., capable of printing 24 sheets of a recording material of a size by laterally passing 24 sheets.

The normal margin of the recording material edge of the image forming apparatus is 5 mm, but the margin of the recording material edge can be arbitrarily set to 1 to 5 mm as a zero edge print.

Using this image forming apparatus, double-sided printing by automatic double-sided printing was performed, and image defects on the back surface were confirmed when the margin of the recording material edge was changed. Confirmation is the proportion of printing in the recording material of A3 size (= printing rate)
Was confirmed by a vertical line image of 20%. The results are shown in Table 1 below. When the image was not chipped, it was marked with ◯, and when the image was chipped, it was marked with x.

[0041]

[Table 1] As shown in the results in Table 1 above, the margin at the tip of the recording material is 1 mm.
However, the problem of image loss does not occur, but at both ends in the conveying direction of the recording material, such as the right edge and the left edge, the water contained in the recording material evaporates as it passes through the fixing device to fix the toner on the first surface. Due to the contraction, image defects occurred in the edge margin of 1 mm. In consideration of the mounting tolerance of each part in the transport section of the image forming apparatus, the thrust, the error of the laser writing position for forming the electrostatic latent image on the photosensitive drum, etc. It is desired that the margin of the material end portion is 2 mm or more.

Further, even if the end margin of the trailing end of the recording material is 3 mm, an image defect occurs. The image deficiency occurs even with 3 mm in contrast to the above-described 1 mm at the right and left margins because the image is stretched when the toner is transferred from the photosensitive drum to the recording material. Even in the rear margin of the image, the mounting tolerance of each part in the transport section, as in the right margin and the left margin,
In consideration of the thrust backlash, the error in the laser writing position for forming the electrostatic latent image on the photosensitive drum, and the like, the rear end margin 4
It is desirable to set it to mm or more.

Therefore, the same confirmation as above is carried out by changing the tolerance of each component, the thrust play, the error of the laser writing position for forming the electrostatic latent image on the photosensitive drum, and the like, and changing the margin of the recording material end. Confirmed the relationship with.

As a result, as the first embodiment of the present invention, in the image forming apparatus equipped with the automatic double-sided printing device,
When the zero edge print is selected as the recording material edge margin smaller than usual, as shown in the flow chart of FIG. 1, the first printing is performed with the selected arbitrary recording material edge margin. The image formation on the back surface, which is a feature of the invention, is a normal recording material edge margin regardless of any selected recording material edge margin.

As described above, as the image forming apparatus for changing the margin of the recording material end portion on the back surface at the time of double-sided printing, it has been confirmed that the image on the recording material is missing and the toner is scattered in the image forming apparatus. , Without any trouble,
I was able to solve the above problem.

In the image forming apparatus described in the first embodiment,
When automatic double-sided printing is performed, the margin of the recording material edge on the back side is
The normal recording material edge margin is used regardless of the leading edge, the trailing edge, the right edge, and the left edge. As described above, the recording material leading edge margin is 5 mm, which is the normal recording material edge margin. Even if the margin of the end portion of the recording material is set to 1 mm as the zero edge print, no image defect occurs on the recording material. This is because when writing an image on the leading edge of the recording material, the position of the leading edge of the recording material is detected by the pair of conveying rollers provided immediately in front of the photosensitive drum and the transfer roller, and writing with the laser is started in synchronization with this. Since the electrostatic latent image is formed on the recording material, the image forming position on the leading edge of the recording material is less affected by the image forming position than the trailing edge, the right edge, and the left edge.

Therefore, as described above, the recording material end margins on the back surface are not uniformly set to the normal recording material end margins regardless of the leading edge, the trailing edge, the right edge, and the left edge, but only the leading edge. Is the recording material edge margin selected as the zero edge print, and the remaining trailing edge, right edge, and left edge of the recording material edge margins are normal recording material edge margins, but the image is missing on the recording material It is possible to prevent the occurrence of adverse effects such as toner scattering in the image forming apparatus due to lack of toner.

Further, as a development system based on such an idea, the margin of the recording material front end on the back surface is the margin of the recording material end selected by the zero edge printing, and the image is most likely to be missing on the recording material. The end margin of the trailing edge of the recording material is a normal end margin. Even if the margins of the right and left ends of the recording material are set to 3 mm, for example, it is possible to prevent the occurrence of an image defect on the recording material and a toner scattering in the image forming apparatus due to the image defect. , High quality printing is guaranteed.

[Second Embodiment] The second embodiment of the present invention will be described below.

In the structure of the image forming apparatus according to the present embodiment, the description of the same parts as those of the conventional example and the first embodiment will be omitted. Further, description of a widely known electrophotographic image forming apparatus will be omitted.

Also in this embodiment, the laser beam printer LBP-930 manufactured by Canon Sales Co., Ltd. described above is used.
Was examined using. Also in this embodiment, the normal recording material end margin is set to 5 mm, and the recording material end margin can be arbitrarily set to 1 to 5 mm as a zero edge print.

In this embodiment, after the recording material on the back surface at the time of the automatic double-sided printing is changed in accordance with the elongation of the image in the recording material conveyance direction, which occurs when the toner image formed on the photosensitive drum is transferred to the recording material. The point is to change the margin.

First, automatic double-sided printing was performed using this image forming apparatus, and it was confirmed that the image on the back surface was missing when the printing rate and the margin of the recording material edge were changed. Confirmation is the proportion of printing in the recording material of A3 size (= printing rate)
As 3%, 5%, 7%, 10%, 20%, 25%,
Recording material when automatic double-sided printing is performed with each vertical line image of 30%, 50%, 75%, 100% (solid black) by changing the margin of the recording material end portion in the range of 1 to 5 mm for each 1 mm. The lack of an image on the back side was confirmed. The results are shown in Tables 2-4 below.
In addition, the recording material end portions of the front end, the rear end, the right end, and the left end are shown.
Similar to the result of the first embodiment shown above, it was rated as O when the image was not missing, and was rated as X when the image was missing.

[0054]

[Table 2]

[0055]

[Table 3]

[0056]

[Table 4] Table 2 (front end margin), Table 3 (rear end margin),
As shown in Table 4 (right edge, left edge margin), each edge of the recording material at the leading edge, the right edge, and the left edge does not depend on the printing rate of the image formed on the recording material, If the margin is provided, there is no occurrence of stains such as image loss and toner scattering inside the image forming apparatus. However, the trailing edge margin of the recording material is affected by the printing rate, and the image stretches when the image is transferred from the photosensitive drum to the recording material. The image is likely to be missing.

FIG. 4 shows an example of the relationship between the image print ratio and the image elongation on an A3 size recording material.

Therefore, in the present invention, in order to solve the above problems, the trailing edge margin of the recording material is changed according to the printing rate of the image.

Specifically, in an image forming apparatus equipped with an automatic double-sided forming device, when the user selects a zero-edge print smaller than a normal recording material end margin, and performs automatic double-sided printing, it is shown in FIG. The image forming apparatus is operated according to such a flow chart and the print ratio and the trailing edge of the trailing edge shown in FIG.

By performing the operation as described above, the rear end margin of the back surface is secured even when the zero edge print is selected and the automatic double-sided print is performed.
The occurrence of image defects does not occur even at the trailing edge of the recording material, the toner does not scatter into the image forming apparatus due to image defects, and it becomes possible to prevent the occurrence of harmful effects and ensure high-quality printing.

[Third Embodiment] FIG. 7 is a flowchart showing the concept of the operation of an image forming apparatus according to the third embodiment of the present invention.

In the present embodiment as well, the description of the configuration of the image forming apparatus, which is the same as in the conventional example and the first and second embodiments, will be omitted. Further, description of a widely known electrophotographic image forming apparatus will be omitted.

Also in the present embodiment, the laser beam printer LBP-930 manufactured by Canon Sales Co., Ltd. described above is used.
, The normal recording material end margin is 5 mm, and for zero edge printing, the recording material end margin is arbitrarily set to 1 to 5 mm.
It can be set in mm.

Using this image forming apparatus, when double-sided printing by automatic double-sided printing is performed and the margins at the edges of the recording material are changed, the image loss on the back surface is caused by the loss of the image on the back surface as described in the second embodiment. Is the same as the result of.

In contrast to the above results, in the third embodiment of the present invention, in order to suppress the elongation of the image that occurs as the printing rate increases, the images are thinned according to the printing rate and the zero edge printing is performed. In this case, the image fits in the recording material. The method will be described in detail below.

For image formation, as shown in FIG. 8, when image information formed by a personal computer or a host computer is sent to a printer or the like which is an image forming apparatus, laser emission is carried out in an image controller section in the printer. Can be converted into a digital signal. The laser emits light according to this digital signal, and an electrostatic latent image is formed on the photosensitive drum. This laser signal determines the minimum unit of image formation and is one pixel (= 1 dot). The unit is the number of pixels formed per inch. In the recent LBP, 600 dpi (dot per)
(inch) is the mainstream. At this 600 dpi, 1
The dot has a size of about 42 μm.

In the present embodiment, in the main scanning direction orthogonal to the recording material conveyance direction, thinning is performed according to the printing rate so that the image to be printed fits within the recording material.

As shown in the second embodiment, the image printing rate and the image elongation are in a substantially proportional relationship, and the relationship between the image elongation per 100 mm in the recording material conveying direction and the printing rate is shown in FIG. Like As you can see, the printing rate is 5
When the image of 0% is thinned out by about 0.8%, the image elongation is almost 0%, and the elongation of the image is the largest, and the printing ratio is 100%, that is, about 1. By thinning out the images for 5%, the elongation of the images can be made almost 0%.

Next, thinning of images will be described. The printing rate that determines the thinning rate of the image is determined from the laser lighting rate in the recording material size when the image signal is converted into a digital signal capable of emitting laser light in the image controller. For example, 600 for A3 size recording material
If an image of dpi is drawn, the printing rate (%) is (42 × 10−6 × 42 × 10−6) × (number of laser lights) / (287 × 10−3 × 410 × 10−3 (record Material size)) is multiplied by 100. Here, the recording material size is such that the margin of the recording material end portion is 5 mm as an area for forming an image.

It is assumed that the printing rate thus obtained is thinned according to the rate of elongation of the image shown in FIG. For example, if the printing rate is 50%, 0.8
Since the image for% is thinned out, the image for 0.3 mm per 100 mm is thinned out. 600 dpi
In the laser beam printer of No. 2, if one line image is thinned out in the main scanning direction, it is 42 μm. Therefore, in order to thin out 0.8 mm, the image stretches to almost 0 if 19 lines are thinned out.
Will be%. However, if 19 lines are thinned out at once, it will have an identifiable effect on the formed image, so it will be thinned out line by line. 100 × 10−3 / 42 × per 100 mm of recording material conveyance direction
Since electrostatic latent images for 10-6 ≈ 2381 lines are formed, it is 2381/19 ≈ 125 to thin out an image for 19 lines on average, so one line for every 125 lines. In other words, 0.042 mm is thinned out per 5.25 mm, and an electrostatic latent image can be formed and can be developed as a toner image without being identified on the formed image.

An example in which the printing rate is 50% has been described as the thinning-out of the image according to the printing rate. However, the same idea is applied to other printing rates, and by thinning out the image, the elongation of the image can be almost 0%. . The relationship is shown in FIG.

As described above, when zero-edge printing is selected and double-sided printing is performed in an image forming apparatus equipped with an automatic double-sided printing device, the image formation on the back side causes the image to expand almost in accordance with the printing rate. By appropriately thinning out the image so as to set it to 0%, a margin that allows zero-edge printing is formed even at the trailing edge of the recording material on the back surface, and the image on the recording material may be missing or the image may not be printed. It is possible to prevent the occurrence of the harmful effect of toner scattering into the image forming apparatus due to the lack thereof, and high-quality printing is guaranteed.

[0073]

As described above, as an effect of the present invention, in an image forming apparatus equipped with an automatic double-sided printing device,
When zero-edge printing is selected as the margin of the recording material that is smaller than normal and automatic double-sided printing is performed, the image on the back side is missing, or toner that is not transferred to the recording material scatters inside the image forming device and An image forming apparatus capable of preventing stains can be obtained.

That is, after an electrostatic latent image is formed on an image carrier made of an optical semiconductor and the developer is developed to visualize the electrostatic latent image, the electrostatic latent image is transferred to a recording material as an unfixed developer, and a pair of An image forming apparatus that permanently fixes a developer image on a recording material by inserting the recording material between rotating bodies and applying heat and pressure, and an automatic image duplexer that automatically forms images on both sides of the recording material. An image forming apparatus capable of switching a recording material end margin provided as an image protection of an image area and a protection area of an image forming apparatus to a recording material end margin narrower than a normal recording material end margin. In, in automatic double-sided image formation, even if you select a recording material edge margin that is narrower than the normal recording material edge margin, the image edge margin on the back side is more than the image edge margin on the recording material surface where the image was first formed. Is wide, or is the normal image margin By using the image forming apparatus characterized by the above, it is possible to prevent the occurrence of chipping of the image printed on the back side and contamination of the inside of the apparatus due to toner not transferred to the recording material being scattered into the image forming apparatus. It has become possible to provide a device.

Further, an electrostatic latent image is formed on an image carrier made of an optical semiconductor, and the electrostatic latent image is visualized by developing the developer, then transferred to a recording material as an unfixed developer, and a pair of An image forming apparatus that permanently fixes a developer image on a recording material by inserting the recording material between rotating bodies and applying heat and pressure, and an automatic image duplexer that automatically forms images on both sides of the recording material. An image forming apparatus capable of switching a recording material end margin provided as an image protection of an image area and a protection area of an image forming apparatus to a recording material end margin narrower than a normal recording material end margin. In, in automatic double-sided image formation, if a recording material edge margin that is narrower than the normal recording material edge margin is selected, a recording material edge larger than the selected recording material edge margin is selected according to the image information on the back side. Image forming apparatus characterized by setting copy margin By doing so, it is possible to provide an image forming apparatus capable of preventing the occurrence of a lack of an image printed on the back surface and a stain in the image value due to toner not transferred to a recording material being scattered in the image forming apparatus. It was

Further, after an electrostatic latent image is formed on the image carrier made of an optical semiconductor and the developer is developed to visualize the electrostatic latent image, the electrostatic latent image is transferred to a recording material as an unfixed developer, and a pair of By inserting the recording material between the rotating bodies and applying heat and pressure,
An image forming apparatus that permanently fixes a developer image on a recording material is provided with an automatic image double-sided device that automatically forms an image on both sides of the recording material, and image protection of an image area, and a protection area of the image forming apparatus, In an image forming apparatus capable of switching the recording material end margin provided as a recording material end margin smaller than a normal recording material end margin, a recording narrower than a normal recording material end margin during automatic double-sided image formation. When the material edge margin is selected, the image to be printed on the back side may be missing by using the image forming apparatus characterized by thinning out the back side image information arbitrarily according to the back side image information. In addition, it is possible to provide an image forming apparatus in which toner that is not transferred to a recording material does not scatter in the image forming apparatus.

[Brief description of drawings]

FIG. 1 is a flowchart diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional image forming apparatus.

FIG. 3 is an explanatory diagram of a margin of a recording material end portion.

FIG. 4 is an explanatory diagram of a second embodiment of the present invention.

FIG. 5 is a flowchart of the second embodiment of the present invention.

FIG. 6 is an explanatory diagram of the second embodiment of the present invention.

FIG. 7 is a flow chart diagram of a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of the third embodiment of the present invention.

FIG. 9 is an explanatory diagram of the second embodiment of the present invention.

FIG. 10 is an explanatory diagram of the third embodiment of the present invention.

[Explanation of symbols]

40 laser scanner 41 Photosensitive drum 42 Primary charger 43 Developing roller 45 Printing process unit 46 transfer roller 48 Conveyor roller pair 50 paper cassettes 51 paper feed roller 52 Transport sheet metal 60 fixer 61 Transport roller pair 70 Output tray 71 Paper ejection roller 80 Automatic double-sided printing device P recording material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B41J 29/52 G03G 21/00 384 G03G 21/00 384 B41J 3/00 SF term (reference) 2C061 AQ06 MM24 2C062 RA06 2C187 AC07 AF01 BF09 DB11 2H027 EA18 EC01 FA13 FA30 FA35 2H028 BB02 BB06 BD03

Claims (5)

[Claims] 1. An electrostatic latent image is formed on an image bearing member made of an optical semiconductor, and the electrostatic latent image is visualized by developing the developer, and then transferred to a recording material as an unfixed developer. An image forming apparatus that permanently fixes a developer image on a recording material by inserting the recording material between rotating bodies and applying heat and pressure, and an automatic image duplexer that automatically forms images on both sides of the recording material. An image forming apparatus capable of switching a recording material end margin provided as an image protection of an image area and a protection area of an image forming apparatus to a recording material end margin narrower than a normal recording material end margin. In the case of automatic double-sided image formation, even if you select a recording material edge margin that is narrower than the normal recording material edge margin, the image edge margin on the back side is larger than the image edge margin on the recording material surface where the image was first formed. Is wide, or it is a normal image margin. An image forming apparatus. 2. In the image forming apparatus, even if a recording material edge margin narrower than a normal recording material edge margin is selected during automatic double-sided image formation, the recording material edge margin on the back surface is The image forming apparatus according to claim 1, wherein, except for the margins, the margins are made wider than the image end margins of the recording material surface on which the image is first formed, or the normal image end margins. 3. In the image forming apparatus, even when a recording material edge margin narrower than a normal recording material edge margin is selected during automatic double-sided image formation, the edge margin of the rear surface of the recording material is 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is wider than an image end margin of a recording material surface on which an image is initially formed, or is a normal image end margin. 4. An electrostatic latent image is formed on an image carrier made of an optical semiconductor, and the electrostatic latent image is visualized by developing the developer, and then transferred to a recording material as an unfixed developer. An image forming apparatus that permanently fixes a developer image on a recording material by inserting the recording material between rotating bodies and applying heat and pressure, and an automatic image duplexer that automatically forms images on both sides of the recording material. An image forming apparatus capable of switching a recording material end margin provided as an image protection of an image area and a protection area of an image forming apparatus to a recording material end margin narrower than a normal recording material end margin. If a recording material edge margin that is narrower than the normal recording material edge margin is selected during automatic double-sided image formation, a recording material edge larger than the selected recording material edge margin is selected according to the image information on the back side. An image forming apparatus characterized by setting a margin of a copy. 5. An electrostatic latent image is formed on an image carrier made of an optical semiconductor, and the electrostatic latent image is visualized by developing the developer, and then transferred to a recording material as an unfixed developer to obtain a pair of images. An image forming apparatus that permanently fixes a developer image on a recording material by inserting the recording material between rotating bodies and applying heat and pressure, and an automatic image duplexer that automatically forms images on both sides of the recording material. An image forming apparatus capable of switching a recording material end margin provided as an image protection of an image area and a protection area of an image forming apparatus to a recording material end margin narrower than a normal recording material end margin. In, in automatic double-sided image formation, when a recording material edge margin that is narrower than a normal recording material edge margin is selected, the image information on the back surface is arbitrarily thinned according to the image information on the back surface. Image forming apparatus.